CA1099731A - Process for preparing tetrahydrofuran - Google Patents
Process for preparing tetrahydrofuranInfo
- Publication number
- CA1099731A CA1099731A CA271,077A CA271077A CA1099731A CA 1099731 A CA1099731 A CA 1099731A CA 271077 A CA271077 A CA 271077A CA 1099731 A CA1099731 A CA 1099731A
- Authority
- CA
- Canada
- Prior art keywords
- distillation column
- tetrahydrofuran
- pressure
- column
- reaction zone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
- C07D307/06—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with only hydrogen atoms or radicals containing only hydrogen and carbon atoms, directly attached to ring carbon atoms
- C07D307/08—Preparation of tetrahydrofuran
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Furan Compounds (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In the process for preparing tetrahydrofuran by the dehydrocyclization of 1,4-butanediol in the presence of a non-volatile acid catalyst, wherein a vapor mixture of water and tetrahydrofuran is continuously taken out from the reaction zone and subjected to azeotropic distillation in at least two distillation columns operated under specified conditions to thereby obtain high quality tetrahydrofuran in a high yield.
In the process for preparing tetrahydrofuran by the dehydrocyclization of 1,4-butanediol in the presence of a non-volatile acid catalyst, wherein a vapor mixture of water and tetrahydrofuran is continuously taken out from the reaction zone and subjected to azeotropic distillation in at least two distillation columns operated under specified conditions to thereby obtain high quality tetrahydrofuran in a high yield.
Description
~L~g973~
BACKGROUND OF THE INVENTION:
This invention relates to an improved process or producing tetrahydrofuran by the dehydrocyclization of 1,4-butanediol in the presence of an acid catalyst. Tetrahydrofuran is a very useful substance as a solvent for high molecular substances~ in particular, polyvinyl chloride, polyvinylidene chloride and it is produced by various processes.
It is known to produce tetrahydrofuran by the dehydro-cyclization of 1,4-butanediol in the presence o an acid catalyst as described in British Patent No. 1170222. However, this process has not achieved a sufficient conversion rate and has not been satlsfac-tory from an industrial point of view. Further, since water and - tetrahydro~uran form an azeotropic mixture, it is difficult to recov-er highly pure tetrahydrofuran in a yield by conventional distillation.
SUMMARY OF THE INVENTION:
-One object of this invention is to provide an industriallyadvantageous process for producing tetrahydrofuran from 1,4-butanediol.
~ Another object of this invention is to provide a : 20 process for producing tetrahydrofuran of high purity in a high yield from crude 1,4-butanediol.
The foregoing objects can easily be attained by taking out, in a gaseous state, the reaction products which are obtained by the dehydrocyclization of l,4-butanediol in the 73~
presence of a non-volatile acid catalyst from a reaction ~p~ce~ and subjecting said reaction products to an azeotropic distillation operation by use of two distillation columns.
BRIEF DESCRIPTION OF THE DRAWING:
The drawing is a flow sheet showing one embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION:
. _ .
1,4-butanediol is a raw material in the process of this invention and its preparation is not restricted to any lo particular method. It is known to prepare 1,4-butanediol by various processes such as hydrogenation of butynediol, or methanolysis of the oxo-reac~ion product of allyl acetate.
It is particular~y preferred to use 1,4-butanediol obtained by hydrolyzing 1,4-diacetoxybutane which is a hydrogenation product of 1,4-diacetoxybutene prepared by the acetoxylation of butadiene.
1,4-diacetoxybutene is prepared by reacting butadiene, acetic acid, and molecular oxygen in the presence of a palladium-based catalyst and, occasionally, in the presence of a solvent, wherein the acetoxylation is carried out by a known process.
1,4-diacetoxybutene is prepared by reacting butadiene, acetic acid, and oxygen or an oxygen-containing gas in the presence of a paLladium-based ca~aLyst in a fixed-bed, fluidized-bed, or suspensoid process.
~L~99`~3:a Various types o~catalysts may be used in the acetoxyla-tion reaction, and preferred catalysts comprise palladium metal in combination with at least one metal co-catalyst seLected from bismuth, selenium~ antimony and tellurium. The above combinations are supported on a suitable carrier. The amount of the catalyst metals are usually selected in a concentra~ion of 0 1 to 20% by weight for palladium and 0.01 to 30% by weight for the metal co-catalyst based on the total weight of the catalyst. The acetoxylation is carried out at a temperature usually within a range of between about 40 to 180C and, preferably between about 60 and 150C under a pressure greater than atmospheric pressure.
Then, water~ acetic acid, high boiling substances and the catalyst are separted rrom the acetoxylation reaction products to produce diacetoxybutene. T'ne thus obtained diacetoxybutene may be exclusively 1,4-diacetoxybutene-2 or a mixture thereof with its isomers such as 3,4-diacetoxybutene-1.
The thus obtained diacetoxybutene is then subjected to the hydrogenation reaction. The feed hydrogen need not always be pure. It may be diluted with an inert gas such as nitrogen or with saturated hydrocarbons such as methane. The hydrogen contents of the diluted gas is not particularly restricted but, ;~ preferably, may be more than lOV/o by volume and, more preferably, more than 50% by volume.
' ~ ~ 9~
The catalyst used for the reaction are the usual hydrogenation cata1ysts, for example, met:als such as Pd, Pt, Ni, Ru, Fe, Os, Rh, Ir, Cr, Mo, W and V, supported on a carrier.
Activated carbon, alumina, silica gel, silica-alumina, clay, bauxite, magnesia, diatomaceous earth, pumice and the like are generally suitable as carriers for the hydrogenation catalysts. Among these, activated carbon is particularly preferred.
The hydrogenation reaction is usually carried out at a temperature of between about 40 and 200C, preferably between about 50 and 100C and under a pressure of between about atmospheric pressure and 200 kg/cm2 gauge, preferably, between about lO
and lO0 kg/cm2 gauge.
The resulting hydrogenation reaction products contain, in addition to diacetoxybutane, l-hydroxy-4-acetoxybutane, high-boiling su'~stances and, perhaps, 4-acetoxybutyraldehyde. These products can all be subjected to the hydrolysis reaction without prior separation.
The hydrolysis of the hydrogenation reaction products is preferably performed in the presence of a solid acid catalyst.
As the solid acid catalyst, cation exchange resins are suitable since they result in the hydrolysis reaction proceeding at a high rate and result in the production of a lesser amount of ;~ by-products. Specifically, strong acidic cation exchange resins of the sulfonic acid type, the matrix of which consists of a styrene-divinylbenzene copolymer, are useful. They may either be gel type resins or porous type resins, for example DIAION*
SKIB*, SK103*, SK106* ( a gel type); PK206*, PK216, PK228*
(a porous type); all manufactured by Mitsubishi Chemical Indus-tries Ltd.
The hydrolysis reaction is performed usually between about 30 and 110C and, preferably between about 40 and 90C.
The pressure used in the hydrolysis reaction is not particularly restricted and is selected usually within the range of between about atomspheric pressure and 10 kg/cm2 gauge.
Water is one of the reactants for the hydrolysis reaction and also functions as a solvent. The amount of water used is more than the stoichiometic amount, and is usually between about 2 and 100 mol, preferably, between about 4 and 50 mol per mol of diacetoxybutane. The reaction is performed in various ways and, usually, by applying a stream of di~
acetoxybutane and water downwardly to a fixed bed filled with the acidic cation exchange resin. The resulting hydrolyzates are then distilled to produce 1,4-butanediol to be used as a raw material in the present process.
Any distillation method can be employed as long as it can remove water, ecetic acid, unreacted diacetoxybutane monohydroxy-monoacetate, partially hydrolyzed products, and, as the case may be~ 1,2- or 1,3-diols, other than 1l4-butanediol, - which are contained in the hydolyzates. That is to say, *denotes trade mark.
~.
~973~
- crude 1,4-butanediol, obtained from the hydrolyzates by distillation to thereby remove those substance having a boiling point lower than ~hat of 1,4-butanediol, can be used directly as the raw material for the process according to this invention.
This invention will be explained referring to the accompaNying drawing. This drawing, and the embodiments shown therein, are for the purposes of illustration only and are not meant to limit or in any way redefine the invention as claimed in the claims appended hereto.
In the accompanying drawing, constituting a part hereof, and in which like reference characters indicate like parts reference (I) is a reaction vesseL, (II) is a first distillation column, (III) a second distillation column and `~
~: .
(IV) a third distillation column.
Any reaction space can be used provided that heating can be effected therein, especially a thermosyphone reboiler type reactor space is suitable. The reaction space may be made of stainle~s steel of SUS 316 and 317 but, preferably, of Hastelloy ttrademark of INC0) since the latter has better corrosion resistance. A glass lined reaction space provides the best corrosion resistance and is best suited for industrial ; use from an economical point of view.
The non-volatile acid catalysts used in this invention include both liquid and solid acids. Liquid acids, including .
~ ~9 ~ ~ 3 ~
inorganic acids such as sulfuric acid or phosphoric acid and organic acids such as benzenesulfonic acid, para-toluene sulfonic acid, trifluoromethane suLfonic acid or the like are usually employed. Sulfuric acid is the most preferred since it is inexpensive and easy to use. The amount of acid required varies depending on the type of acidO It is difficult to accurately specify a range therefor, although it is usuaLly applied in an amount of between about O.L and 99 parts by weight and, preferably, 5 to 90 parts by weight per 100 parts by weight of the liquid components contained in the reaction vessel. The liquid acid may either be continuously fed to the reaction vessel with the crude 1, 4 butanediol or be placed in the reaction vessel prlor to the addition of the raw material In the continuous process, the 1,4-butanediol is fed together with the acid as the catalyst to the reaction vessel (I) ~hrough conduit 1. The reaction vessel (I) is kept at a temperature which is sufficient to maintain a pressure therein at a level such that the tetrahydrofuran and water produced in said vessel can move in the vapor phase to the first distillation colum~ due to autogenetic pressure. The reaction temperature is therefore determined in correlation with the operation pressure in the first distillation column and should usually be above about 90C. However, the temperature is preferably less than about 220C and , more preferably, from between about 110 and 160C since excessively high temperatures ~g~731 will cause undesirable side reactions.
The reaction pressure should be a Little higher than the pressure in the first distillation column and usually is selected within the range of up to 3 kg,/cm gauge.
The mixed vapor effluent from the upper portion of the reaction vessel, containing about equimolar amounts of tetrahydrofuran and water, is fed through cond-lit 3 to the first distillation coLumn (II). On the other hand, high boiling substances (which have been supplied togekher with the raw material and produced as by-products in the reaction), spent catalysts, and the like are properly discharged from the reaction system through conduit 2.
A vapor mixture of tetrahydrofuran and watPr fed from the reactor and an azeotropic mixture of tetrahydrouran and water recycled from the second distillation column are supplied to the first distillation column for the purpose of effecting distillation The first distillation column is operated with 5 to 30 theoretical plates, under a pressure of between about atmospheric pressure and 3 kg/cm2 gauge and with a reflux rati~ of between about 0.5 and 5, preferably between about 1 and 3. An azeotropic mixture of tetrahydrofuran and water ~THF : H2O = 81 : 19 - 74 : 26, in molar ratio) is distilled from the top of the column and supplied through conduit 5 to the second distillation column. Then, water is removed from the bottom of the second distillation column through conduit 4. The ~ 7 3 ~
effluent from the top of the first distillation column. is pressurized by means of a pump and supplied to the second distillation column (III). The second distillation column is operated with 5 to 30 theoretical plates, maintained under a pressure higher than the first distillation column This pressure range is from between about 3 and 23 kg/cm2 gauge, preferably, 5 to 18 kg/cm2 gauge, and with a reflux ratio o between about : 0.5 and 5, preferably, between about 1 and 3.
~; An azeotropic mixture of tetrahydrofuran and water (THF : H20 = 74 : 26 - 53 47, preferably, 69 : 31 - 55 : 453 is distilled from the top of the second distillation column and circulated to the first distillation column and, tetrahydrofuran, .
substantialLy free from water, is obtained from the botton of the second distillation coLumn..
~ 1 While the thus obtained tetrahydrofuran has a considerably high purity and can be commercially useful as i9, it can be further purified if required. For instance, the product discharged from the second distillation column can be suppLied through conduit 6 to a third distillation column (IV) : 2Q to~produce tetrahydrofuran of higher purity through conduit 7.
:
~ : The third distillation column is usually operated with 10 to 30 . ~:
' ;~ theoretlcal platesg under a~pressure equal to or slightly higher : than atmospheric pressure and with a reflux ratio of 0.5 to 2Ø
If the product discharged from the bottom of the third distillation column LS recycLed through conduit 8 to the dehydrocyclization system, additional industrial advantages can : be realized. For example, in dehydrocyclization, n-butyraldehyde 1~973~
is inevitably produced as a by-product and cannot easily be separated completely by distillation from tetrahydrofuran. On the other hand, since n-butyraldehyde is unstable in the presence of the acidic catalyst and changes into higher boiling substances and the like1 the concentration of n-butyraldehyde in the dehydrocyclization reaction system does not exceed a certain level depending on the reaction conditions. Therefore, by recycling the product discharged from the bottom of the third distillation column, having a high n-butyraLdehyde content, that amount of n-butyraldehyde in the reaction product can be kept to an acceptably low level thereby preventing a decrease in the yield of tetrahydrofuran and improving the purity thereof.
As described above, according to the process of this invention, tetrahydrofuran of very high quality can be obtained from the bottom of a distillation column by taking out the reaction products in a gaseous state rom the reaction vessel and subjecting them directly to distillation carried out in two distillation columns under specified conditions.
Moreover, since the reaction products are ~ransferred in their gaseous tate, the present reaction can be performed with no difficulty even when substances having boiling points similar to or higher than the boiling point of 1,4-butanediol are present in the 1,4-butanediol. Therefore, the present invention ~ ~ 9 provides economical advantages.
The process according to this invention is described more specifically hereina~ter by way o~ a preferred embodiment.
It should be understood, however, that the invention is in no way limited to such embodiment.
Example 1 .
Diacetoxybutene, which had been prepared by catalytically reacting butadiene, acetic acid and oxygen-containing gas with a palladium-based catalyst at 80 to 100C, was hydrogenated in the ; 10 presence of a palladium catalyst carried on activated carbon to produce diacetoxybutane having the composition set for~h below.
The resulting diacetoxybutane was then hydrolyzed in the presence of a cation exchange resin, DIAION SKIB, (trade mark, manufactured by Mitsubishi Chemical Industries L,td.) at about 60C and subjected to distillation to prepare crude 1,4-butanediol. This crude product contained 98.5% by weight of 1,4-butanediol, 0.7%
by weight of high boiling substances and 0.8% by weight of other substances.
Composition of Diacetoxybutane ~o 1,4-diacetoxybutane 86.3% by weight hydroxy-4-acetoxybutane4.4% by weight Acetoxybutyraldehyde 0.2% by weight ~utylacetate 1.7% by weight High boiling substances0.4% by weight ; 25 10.0 kg of the thus prepared crude 1~4-butanediol was mixed with 10 g of H2S04 and fed to reaction vessel (I) at a rate of 0.64 kg/hr. The reactor is made of Hastelloy (trade ~G~9~t~3 ~
mark of INC0), and has a 50 mm inner diarneter and a 1 m Length and is provided with a steam heating type reboiler composed of three pipes each having a 10 mm outer diameter and a 8 mm inner diameter. The steam supplied to the reboiler was conditioned to maintain the inside temperature of the reaction vessel at 130C. A mixture o:E tetrahydrofuran and water, having a 1 : 1 molar ratio, was discharged in the vapor phase from the top of the reactor at a r~te of 0 63 kg/hr. The mixed vapor was fed by autogenetic pressure to the first distillation column (II) (50 mm in inner diameter and 10 m in height, filled with Dickson pakings). The distillation column was operated under atmospheric pressure with a reflux ratio of 2.0 to obtain a liquid distillate comprising 94 4% by weight of tetrahydrofuran, 5.6% by weight of water and 190 ppm by weight of n-butyraldehyde I5 at 0.893 kg/hr from the top thereof. The distillate was then sent by way of a pump to a second distillation column (150 mm in inner diameter and 10 m in height, filled with Dickson packings), distilled under a pressure of 7 kg/cm2 gauge with a reflux ratio of 4Ø The liquid distillate, comprising 87.2% by weight of tetrahy~rofuran and 12.8% by weight of water was discharged rom the top of the column at a rate of 0.391 kg/hr and then recycled to the first distillation column. While on the other hand, tetrahydrofuran with a purity of greater than99.95 wt%, was obtained as the product at a rate of 0.502 kg/hr rom the bottom of the second distillation column. The product contained ~9~q3~
200 ppm o n-butyraldehyde, The product discharged rom the seconcl distillation column, at the rate of 0.502 kg/hr, was then supplied by means of a pump to a third distillation column (IV) (1500 mm in S inner diameter, 10 m in height and illed with Dickson packings).
This column was operated under atmospheric pressure with a refLux ratio of 2.0 to obtain tetrahydrofuran with a purity of 99.97 ; ~ wt% as a liquid distillate at a rate of 0,477 kg/hr rom the top of thereof, The n-butyraldehyde content in the distillate was ~:
130 ppm by weight, A product containing 1500 ppm by weight of n-butyraldehyde was produced at a rate o 0.025 kg/hr rom the s bottom of the column (IV). ~ihen the above-described product was recycled to the reaction zone, the butyraldehyde content of the distillate~ rom the third distillation column was reduced to :
' 15 between about 120 and 140 ppm by weight, :`
~: ' ::
BACKGROUND OF THE INVENTION:
This invention relates to an improved process or producing tetrahydrofuran by the dehydrocyclization of 1,4-butanediol in the presence of an acid catalyst. Tetrahydrofuran is a very useful substance as a solvent for high molecular substances~ in particular, polyvinyl chloride, polyvinylidene chloride and it is produced by various processes.
It is known to produce tetrahydrofuran by the dehydro-cyclization of 1,4-butanediol in the presence o an acid catalyst as described in British Patent No. 1170222. However, this process has not achieved a sufficient conversion rate and has not been satlsfac-tory from an industrial point of view. Further, since water and - tetrahydro~uran form an azeotropic mixture, it is difficult to recov-er highly pure tetrahydrofuran in a yield by conventional distillation.
SUMMARY OF THE INVENTION:
-One object of this invention is to provide an industriallyadvantageous process for producing tetrahydrofuran from 1,4-butanediol.
~ Another object of this invention is to provide a : 20 process for producing tetrahydrofuran of high purity in a high yield from crude 1,4-butanediol.
The foregoing objects can easily be attained by taking out, in a gaseous state, the reaction products which are obtained by the dehydrocyclization of l,4-butanediol in the 73~
presence of a non-volatile acid catalyst from a reaction ~p~ce~ and subjecting said reaction products to an azeotropic distillation operation by use of two distillation columns.
BRIEF DESCRIPTION OF THE DRAWING:
The drawing is a flow sheet showing one embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION:
. _ .
1,4-butanediol is a raw material in the process of this invention and its preparation is not restricted to any lo particular method. It is known to prepare 1,4-butanediol by various processes such as hydrogenation of butynediol, or methanolysis of the oxo-reac~ion product of allyl acetate.
It is particular~y preferred to use 1,4-butanediol obtained by hydrolyzing 1,4-diacetoxybutane which is a hydrogenation product of 1,4-diacetoxybutene prepared by the acetoxylation of butadiene.
1,4-diacetoxybutene is prepared by reacting butadiene, acetic acid, and molecular oxygen in the presence of a palladium-based catalyst and, occasionally, in the presence of a solvent, wherein the acetoxylation is carried out by a known process.
1,4-diacetoxybutene is prepared by reacting butadiene, acetic acid, and oxygen or an oxygen-containing gas in the presence of a paLladium-based ca~aLyst in a fixed-bed, fluidized-bed, or suspensoid process.
~L~99`~3:a Various types o~catalysts may be used in the acetoxyla-tion reaction, and preferred catalysts comprise palladium metal in combination with at least one metal co-catalyst seLected from bismuth, selenium~ antimony and tellurium. The above combinations are supported on a suitable carrier. The amount of the catalyst metals are usually selected in a concentra~ion of 0 1 to 20% by weight for palladium and 0.01 to 30% by weight for the metal co-catalyst based on the total weight of the catalyst. The acetoxylation is carried out at a temperature usually within a range of between about 40 to 180C and, preferably between about 60 and 150C under a pressure greater than atmospheric pressure.
Then, water~ acetic acid, high boiling substances and the catalyst are separted rrom the acetoxylation reaction products to produce diacetoxybutene. T'ne thus obtained diacetoxybutene may be exclusively 1,4-diacetoxybutene-2 or a mixture thereof with its isomers such as 3,4-diacetoxybutene-1.
The thus obtained diacetoxybutene is then subjected to the hydrogenation reaction. The feed hydrogen need not always be pure. It may be diluted with an inert gas such as nitrogen or with saturated hydrocarbons such as methane. The hydrogen contents of the diluted gas is not particularly restricted but, ;~ preferably, may be more than lOV/o by volume and, more preferably, more than 50% by volume.
' ~ ~ 9~
The catalyst used for the reaction are the usual hydrogenation cata1ysts, for example, met:als such as Pd, Pt, Ni, Ru, Fe, Os, Rh, Ir, Cr, Mo, W and V, supported on a carrier.
Activated carbon, alumina, silica gel, silica-alumina, clay, bauxite, magnesia, diatomaceous earth, pumice and the like are generally suitable as carriers for the hydrogenation catalysts. Among these, activated carbon is particularly preferred.
The hydrogenation reaction is usually carried out at a temperature of between about 40 and 200C, preferably between about 50 and 100C and under a pressure of between about atmospheric pressure and 200 kg/cm2 gauge, preferably, between about lO
and lO0 kg/cm2 gauge.
The resulting hydrogenation reaction products contain, in addition to diacetoxybutane, l-hydroxy-4-acetoxybutane, high-boiling su'~stances and, perhaps, 4-acetoxybutyraldehyde. These products can all be subjected to the hydrolysis reaction without prior separation.
The hydrolysis of the hydrogenation reaction products is preferably performed in the presence of a solid acid catalyst.
As the solid acid catalyst, cation exchange resins are suitable since they result in the hydrolysis reaction proceeding at a high rate and result in the production of a lesser amount of ;~ by-products. Specifically, strong acidic cation exchange resins of the sulfonic acid type, the matrix of which consists of a styrene-divinylbenzene copolymer, are useful. They may either be gel type resins or porous type resins, for example DIAION*
SKIB*, SK103*, SK106* ( a gel type); PK206*, PK216, PK228*
(a porous type); all manufactured by Mitsubishi Chemical Indus-tries Ltd.
The hydrolysis reaction is performed usually between about 30 and 110C and, preferably between about 40 and 90C.
The pressure used in the hydrolysis reaction is not particularly restricted and is selected usually within the range of between about atomspheric pressure and 10 kg/cm2 gauge.
Water is one of the reactants for the hydrolysis reaction and also functions as a solvent. The amount of water used is more than the stoichiometic amount, and is usually between about 2 and 100 mol, preferably, between about 4 and 50 mol per mol of diacetoxybutane. The reaction is performed in various ways and, usually, by applying a stream of di~
acetoxybutane and water downwardly to a fixed bed filled with the acidic cation exchange resin. The resulting hydrolyzates are then distilled to produce 1,4-butanediol to be used as a raw material in the present process.
Any distillation method can be employed as long as it can remove water, ecetic acid, unreacted diacetoxybutane monohydroxy-monoacetate, partially hydrolyzed products, and, as the case may be~ 1,2- or 1,3-diols, other than 1l4-butanediol, - which are contained in the hydolyzates. That is to say, *denotes trade mark.
~.
~973~
- crude 1,4-butanediol, obtained from the hydrolyzates by distillation to thereby remove those substance having a boiling point lower than ~hat of 1,4-butanediol, can be used directly as the raw material for the process according to this invention.
This invention will be explained referring to the accompaNying drawing. This drawing, and the embodiments shown therein, are for the purposes of illustration only and are not meant to limit or in any way redefine the invention as claimed in the claims appended hereto.
In the accompanying drawing, constituting a part hereof, and in which like reference characters indicate like parts reference (I) is a reaction vesseL, (II) is a first distillation column, (III) a second distillation column and `~
~: .
(IV) a third distillation column.
Any reaction space can be used provided that heating can be effected therein, especially a thermosyphone reboiler type reactor space is suitable. The reaction space may be made of stainle~s steel of SUS 316 and 317 but, preferably, of Hastelloy ttrademark of INC0) since the latter has better corrosion resistance. A glass lined reaction space provides the best corrosion resistance and is best suited for industrial ; use from an economical point of view.
The non-volatile acid catalysts used in this invention include both liquid and solid acids. Liquid acids, including .
~ ~9 ~ ~ 3 ~
inorganic acids such as sulfuric acid or phosphoric acid and organic acids such as benzenesulfonic acid, para-toluene sulfonic acid, trifluoromethane suLfonic acid or the like are usually employed. Sulfuric acid is the most preferred since it is inexpensive and easy to use. The amount of acid required varies depending on the type of acidO It is difficult to accurately specify a range therefor, although it is usuaLly applied in an amount of between about O.L and 99 parts by weight and, preferably, 5 to 90 parts by weight per 100 parts by weight of the liquid components contained in the reaction vessel. The liquid acid may either be continuously fed to the reaction vessel with the crude 1, 4 butanediol or be placed in the reaction vessel prlor to the addition of the raw material In the continuous process, the 1,4-butanediol is fed together with the acid as the catalyst to the reaction vessel (I) ~hrough conduit 1. The reaction vessel (I) is kept at a temperature which is sufficient to maintain a pressure therein at a level such that the tetrahydrofuran and water produced in said vessel can move in the vapor phase to the first distillation colum~ due to autogenetic pressure. The reaction temperature is therefore determined in correlation with the operation pressure in the first distillation column and should usually be above about 90C. However, the temperature is preferably less than about 220C and , more preferably, from between about 110 and 160C since excessively high temperatures ~g~731 will cause undesirable side reactions.
The reaction pressure should be a Little higher than the pressure in the first distillation column and usually is selected within the range of up to 3 kg,/cm gauge.
The mixed vapor effluent from the upper portion of the reaction vessel, containing about equimolar amounts of tetrahydrofuran and water, is fed through cond-lit 3 to the first distillation coLumn (II). On the other hand, high boiling substances (which have been supplied togekher with the raw material and produced as by-products in the reaction), spent catalysts, and the like are properly discharged from the reaction system through conduit 2.
A vapor mixture of tetrahydrofuran and watPr fed from the reactor and an azeotropic mixture of tetrahydrouran and water recycled from the second distillation column are supplied to the first distillation column for the purpose of effecting distillation The first distillation column is operated with 5 to 30 theoretical plates, under a pressure of between about atmospheric pressure and 3 kg/cm2 gauge and with a reflux rati~ of between about 0.5 and 5, preferably between about 1 and 3. An azeotropic mixture of tetrahydrofuran and water ~THF : H2O = 81 : 19 - 74 : 26, in molar ratio) is distilled from the top of the column and supplied through conduit 5 to the second distillation column. Then, water is removed from the bottom of the second distillation column through conduit 4. The ~ 7 3 ~
effluent from the top of the first distillation column. is pressurized by means of a pump and supplied to the second distillation column (III). The second distillation column is operated with 5 to 30 theoretical plates, maintained under a pressure higher than the first distillation column This pressure range is from between about 3 and 23 kg/cm2 gauge, preferably, 5 to 18 kg/cm2 gauge, and with a reflux ratio o between about : 0.5 and 5, preferably, between about 1 and 3.
~; An azeotropic mixture of tetrahydrofuran and water (THF : H20 = 74 : 26 - 53 47, preferably, 69 : 31 - 55 : 453 is distilled from the top of the second distillation column and circulated to the first distillation column and, tetrahydrofuran, .
substantialLy free from water, is obtained from the botton of the second distillation coLumn..
~ 1 While the thus obtained tetrahydrofuran has a considerably high purity and can be commercially useful as i9, it can be further purified if required. For instance, the product discharged from the second distillation column can be suppLied through conduit 6 to a third distillation column (IV) : 2Q to~produce tetrahydrofuran of higher purity through conduit 7.
:
~ : The third distillation column is usually operated with 10 to 30 . ~:
' ;~ theoretlcal platesg under a~pressure equal to or slightly higher : than atmospheric pressure and with a reflux ratio of 0.5 to 2Ø
If the product discharged from the bottom of the third distillation column LS recycLed through conduit 8 to the dehydrocyclization system, additional industrial advantages can : be realized. For example, in dehydrocyclization, n-butyraldehyde 1~973~
is inevitably produced as a by-product and cannot easily be separated completely by distillation from tetrahydrofuran. On the other hand, since n-butyraldehyde is unstable in the presence of the acidic catalyst and changes into higher boiling substances and the like1 the concentration of n-butyraldehyde in the dehydrocyclization reaction system does not exceed a certain level depending on the reaction conditions. Therefore, by recycling the product discharged from the bottom of the third distillation column, having a high n-butyraLdehyde content, that amount of n-butyraldehyde in the reaction product can be kept to an acceptably low level thereby preventing a decrease in the yield of tetrahydrofuran and improving the purity thereof.
As described above, according to the process of this invention, tetrahydrofuran of very high quality can be obtained from the bottom of a distillation column by taking out the reaction products in a gaseous state rom the reaction vessel and subjecting them directly to distillation carried out in two distillation columns under specified conditions.
Moreover, since the reaction products are ~ransferred in their gaseous tate, the present reaction can be performed with no difficulty even when substances having boiling points similar to or higher than the boiling point of 1,4-butanediol are present in the 1,4-butanediol. Therefore, the present invention ~ ~ 9 provides economical advantages.
The process according to this invention is described more specifically hereina~ter by way o~ a preferred embodiment.
It should be understood, however, that the invention is in no way limited to such embodiment.
Example 1 .
Diacetoxybutene, which had been prepared by catalytically reacting butadiene, acetic acid and oxygen-containing gas with a palladium-based catalyst at 80 to 100C, was hydrogenated in the ; 10 presence of a palladium catalyst carried on activated carbon to produce diacetoxybutane having the composition set for~h below.
The resulting diacetoxybutane was then hydrolyzed in the presence of a cation exchange resin, DIAION SKIB, (trade mark, manufactured by Mitsubishi Chemical Industries L,td.) at about 60C and subjected to distillation to prepare crude 1,4-butanediol. This crude product contained 98.5% by weight of 1,4-butanediol, 0.7%
by weight of high boiling substances and 0.8% by weight of other substances.
Composition of Diacetoxybutane ~o 1,4-diacetoxybutane 86.3% by weight hydroxy-4-acetoxybutane4.4% by weight Acetoxybutyraldehyde 0.2% by weight ~utylacetate 1.7% by weight High boiling substances0.4% by weight ; 25 10.0 kg of the thus prepared crude 1~4-butanediol was mixed with 10 g of H2S04 and fed to reaction vessel (I) at a rate of 0.64 kg/hr. The reactor is made of Hastelloy (trade ~G~9~t~3 ~
mark of INC0), and has a 50 mm inner diarneter and a 1 m Length and is provided with a steam heating type reboiler composed of three pipes each having a 10 mm outer diameter and a 8 mm inner diameter. The steam supplied to the reboiler was conditioned to maintain the inside temperature of the reaction vessel at 130C. A mixture o:E tetrahydrofuran and water, having a 1 : 1 molar ratio, was discharged in the vapor phase from the top of the reactor at a r~te of 0 63 kg/hr. The mixed vapor was fed by autogenetic pressure to the first distillation column (II) (50 mm in inner diameter and 10 m in height, filled with Dickson pakings). The distillation column was operated under atmospheric pressure with a reflux ratio of 2.0 to obtain a liquid distillate comprising 94 4% by weight of tetrahydrofuran, 5.6% by weight of water and 190 ppm by weight of n-butyraldehyde I5 at 0.893 kg/hr from the top thereof. The distillate was then sent by way of a pump to a second distillation column (150 mm in inner diameter and 10 m in height, filled with Dickson packings), distilled under a pressure of 7 kg/cm2 gauge with a reflux ratio of 4Ø The liquid distillate, comprising 87.2% by weight of tetrahy~rofuran and 12.8% by weight of water was discharged rom the top of the column at a rate of 0.391 kg/hr and then recycled to the first distillation column. While on the other hand, tetrahydrofuran with a purity of greater than99.95 wt%, was obtained as the product at a rate of 0.502 kg/hr rom the bottom of the second distillation column. The product contained ~9~q3~
200 ppm o n-butyraldehyde, The product discharged rom the seconcl distillation column, at the rate of 0.502 kg/hr, was then supplied by means of a pump to a third distillation column (IV) (1500 mm in S inner diameter, 10 m in height and illed with Dickson packings).
This column was operated under atmospheric pressure with a refLux ratio of 2.0 to obtain tetrahydrofuran with a purity of 99.97 ; ~ wt% as a liquid distillate at a rate of 0,477 kg/hr rom the top of thereof, The n-butyraldehyde content in the distillate was ~:
130 ppm by weight, A product containing 1500 ppm by weight of n-butyraldehyde was produced at a rate o 0.025 kg/hr rom the s bottom of the column (IV). ~ihen the above-described product was recycled to the reaction zone, the butyraldehyde content of the distillate~ rom the third distillation column was reduced to :
' 15 between about 120 and 140 ppm by weight, :`
~: ' ::
Claims (25)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing tetrahydrofuran by dehydrocyclizing 1,4-butanediol in the presence of an acid catalyst comprising:
a) reacting 1,4-butanediol and a non-volatile acid catalyst to produce tetrahydrofuran and water in a reaction zone serially connected to a first distil-lation column and second distillation column at a temperature such that said tetrahydrofuran and said water are a gaseous mixture at a pressure higher than that in said first distillation column;
b) transferring said gaseous mixture to said first distillation column;
c) exposing said gaseous mixture in said first distil-lation column to a pressure between about atmospheric pressure and 3 kg/cm2 gauge and a reflux ratio of between about 0.5 and 5.0, whereby a first azeotropic mixture is formed;
d) transferring said first azeotropic mixture to said second distillation column;
e) exposing said first azeotropic mixture in said second distillation column to a pressure higher than that in said first distillation column by 3 to 20 kg/cm2 gauge and a reflux ratio between 0.5 and 5.0 whereby a second azeotropic mixture is formed;
f) removing tetrahydrofuran from said second distillation column;
g) recycling said second azeotropic mixture to said first distillation column;
h) transferring tetrahydrofuran from said second distil-lation column to a third distillation column;
i) exposing the tetrahydrofuran under atmospheric pressure or a pressure slightly higher than atmos-pheric pressure and a reflux ratio of between about 0.5 and 2.0 to produce substantially pure tetra-hydrofuran and a discharged product;
j) removing said substantially pure tetrahydrofuran from an upper portion of said third distillation column;
and k) recycling said discharge product from a lower portion of said third distillation column to said reaction zone.
a) reacting 1,4-butanediol and a non-volatile acid catalyst to produce tetrahydrofuran and water in a reaction zone serially connected to a first distil-lation column and second distillation column at a temperature such that said tetrahydrofuran and said water are a gaseous mixture at a pressure higher than that in said first distillation column;
b) transferring said gaseous mixture to said first distillation column;
c) exposing said gaseous mixture in said first distil-lation column to a pressure between about atmospheric pressure and 3 kg/cm2 gauge and a reflux ratio of between about 0.5 and 5.0, whereby a first azeotropic mixture is formed;
d) transferring said first azeotropic mixture to said second distillation column;
e) exposing said first azeotropic mixture in said second distillation column to a pressure higher than that in said first distillation column by 3 to 20 kg/cm2 gauge and a reflux ratio between 0.5 and 5.0 whereby a second azeotropic mixture is formed;
f) removing tetrahydrofuran from said second distillation column;
g) recycling said second azeotropic mixture to said first distillation column;
h) transferring tetrahydrofuran from said second distil-lation column to a third distillation column;
i) exposing the tetrahydrofuran under atmospheric pressure or a pressure slightly higher than atmos-pheric pressure and a reflux ratio of between about 0.5 and 2.0 to produce substantially pure tetra-hydrofuran and a discharged product;
j) removing said substantially pure tetrahydrofuran from an upper portion of said third distillation column;
and k) recycling said discharge product from a lower portion of said third distillation column to said reaction zone.
2. The process of claim 1 wherein the temperature in said reaction zone is above 90°C and below 220°C.
3. The process of claim 2 wherein said temperature is between about 110°C and 160°C.
4. The process of claim 1 wherein the pressure in said reaction zone is between 0 and 3 kg/cm2 gauge.
5. The process of claim 1 wherein the reflux ratio in said first distillation column is between about 1 and 3.
6. The process of claim 1 wherein the pressure in said second distillation column is between about 3 and 23 kg/cm2 gauge and said reflux ratio is between about 1 and 3.
7. The process of claim 6 wherein said pressure in second distillation column is between about 5 and 18 kg/cm gauge.
8. The process of claim 1 wherein said acid catalyst is selected from the group consisting of sulfuric acid, phosphoric acid, benzenesulfonic acid, paratoluene sulfonic acid, and trifluoromethane sulfonic acid.
9. The process of claim 1 wherein said 1,4-butanediol and said catalyst are fed continuously to said reaction zone.
10. The process of claim 8 wherein said acid catalyst is sulfuric acid.
11. The process of claim 1 wherein the amount of said acid catalyst is between about 0.1 and 99 parts per 100 parts by weight of the liquid components in said reaction zone.
12. The process of claim 1 further comprising removing said first azeotropic mixture from an upper portion of said first distillation column and water from a lower portion of said first distillation column and removing said second azeotropic mixture from an upper portion of said second distillation column and tetrahydrofuran from a lower portion of said second distillation column.
13. A process for preparing tetrahydrofuran by dehydrocyclizing 1,4-butanediol in the presence of an non-volatile acid catalyst comprising:
a) reacting in a reaction zone 1,4-butanediol and an non-volatile acid catalyst in an amount of between about 0.1 and 99 parts by weight per 100 parts by weight of the liquid components in said reaction zone, said acid catalyst bieng selected from the group consisting of sulfuric acid, phosphoric acid, benzenesulfonic acid, paratoluene sulfonic acid and trifluoromethane sulfonic acid at a temperature above 90°C and below 220°C and a pressure above that of said first distillation column and between 0 and 3 kg/cm2 gauge to produce a gaseous mixture of tetrahydrofuran and water;
b) transferring said gaseous mixture from an upper portion of said reaction zone to a first distillation column;
c) exposing said gaseous mixture in said first distillation column to a pressure between about atmospheric pressure and 3 kg/cm2 gauge and a reflux ratio of between about 0.5 and 5.0 whereby a first azeotropic mixture and water are formed;
d) transferring said first azeotropic mixture from an upper portion of said first distillation column to said second distillation column;
e) removing water from a lower portion of said first distillation column;
f) exposing said first azeotropic mixture in said second distillation column to a pressure of between about 3 and 23 kg/cm2 gauge and a reflux ratio of between about 0.5 and 5.0, whereby a second azeotropic mixture is formed;
g) removing tetrahydrofuran from a lower portion of said second distillation column, and recycling said second azeotropic mixture to said first distillation column.
h) transferring tetrahydrofuran from said second distil-lation column to a third distillation column;
i) exposing the tetrahydrofuran under atmospheric pressure or a pressure slightly higher than atmospheric pressure and a reflux ratio of between about 0.5 and 2.0 to produce substantially pure tetrahydrofuran and a discharged product;
j) removing said substantially pure tetrahydrofuran from an upper portion of said third distillation column; and k) recycling said discharged product from a lower portion of said third distillation column to said reaction zone.
a) reacting in a reaction zone 1,4-butanediol and an non-volatile acid catalyst in an amount of between about 0.1 and 99 parts by weight per 100 parts by weight of the liquid components in said reaction zone, said acid catalyst bieng selected from the group consisting of sulfuric acid, phosphoric acid, benzenesulfonic acid, paratoluene sulfonic acid and trifluoromethane sulfonic acid at a temperature above 90°C and below 220°C and a pressure above that of said first distillation column and between 0 and 3 kg/cm2 gauge to produce a gaseous mixture of tetrahydrofuran and water;
b) transferring said gaseous mixture from an upper portion of said reaction zone to a first distillation column;
c) exposing said gaseous mixture in said first distillation column to a pressure between about atmospheric pressure and 3 kg/cm2 gauge and a reflux ratio of between about 0.5 and 5.0 whereby a first azeotropic mixture and water are formed;
d) transferring said first azeotropic mixture from an upper portion of said first distillation column to said second distillation column;
e) removing water from a lower portion of said first distillation column;
f) exposing said first azeotropic mixture in said second distillation column to a pressure of between about 3 and 23 kg/cm2 gauge and a reflux ratio of between about 0.5 and 5.0, whereby a second azeotropic mixture is formed;
g) removing tetrahydrofuran from a lower portion of said second distillation column, and recycling said second azeotropic mixture to said first distillation column.
h) transferring tetrahydrofuran from said second distil-lation column to a third distillation column;
i) exposing the tetrahydrofuran under atmospheric pressure or a pressure slightly higher than atmospheric pressure and a reflux ratio of between about 0.5 and 2.0 to produce substantially pure tetrahydrofuran and a discharged product;
j) removing said substantially pure tetrahydrofuran from an upper portion of said third distillation column; and k) recycling said discharged product from a lower portion of said third distillation column to said reaction zone.
14. The process of claim 13 wherein the temperature in said reaction column is between about 110°C and 160°C.
15. The process of claim 13 wherein the reflux ratio in said first distillation column is between about 1 and 3.
16. The process of claim 13 wherein said first azeotropic mixture has a molar ratio of THF : H2O of between about 81 : 19 and 74 : 26.
17. The process of claim 13 wherein the pressure in said second distillation column is between about 5 and 18 kg/cm2 gauge and said reflux ratio is between about 1 and 3.
18. The process of claim 13 wherein said second azeotropic mixture has a molar ratio of THF : H2O of between about 74 : 26 and 53 : 47.
19. The process of claim 18 wherein said molar ratio is between about 69 : 31 and 55 : 45.
20. The process of claim 13 wherein 1,4-butanediol and said acid catalyst are fed continuously to said reaction zone.
21. The process of claim 13 wherein said first distillation column is a column having 5 to 30 theoretical plates.
22. The process of claim 13 wherein said second distillation column is a column having 5 to 30 theroetical plates.
23. The process of claim 13 wherein said third distillation column is a column having 10 to 30 theoretical plates.
24. The process of claim 13 wherein said acid cataylst is sulfuric acid.
25. The process of claim 13 wherein the amount of said acid catalyst is between about 5 and 90 parts by weight per 100 parts by weight of the liquid components in said reaction zone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11078/1976 | 1976-02-04 | ||
| JP1107876A JPS5293763A (en) | 1976-02-04 | 1976-02-04 | Preparation of tetrahydrofuran |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1099731A true CA1099731A (en) | 1981-04-21 |
Family
ID=11767935
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA271,077A Expired CA1099731A (en) | 1976-02-04 | 1977-02-04 | Process for preparing tetrahydrofuran |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4093633A (en) |
| JP (1) | JPS5293763A (en) |
| CA (1) | CA1099731A (en) |
| DE (1) | DE2704500C2 (en) |
| FR (1) | FR2340314A1 (en) |
| GB (1) | GB1502591A (en) |
| IT (1) | IT1082522B (en) |
| NL (1) | NL187911C (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2927931C3 (en) * | 1979-07-11 | 1982-03-11 | Chemische Werke Hüls AG, 4370 Marl | Process for the continuous separation of methanol from mixtures of tetrahydrofuran with methanol and water |
| US4348262A (en) * | 1980-05-19 | 1982-09-07 | E. I. Du Pont De Nemours And Company | Refining tetrahydrofuran |
| US4257961A (en) * | 1980-06-11 | 1981-03-24 | E. I. Du Pont De Nemours And Company | Purification of tetrahydrofuran |
| US4413136A (en) * | 1982-08-02 | 1983-11-01 | E. I. Du Pont De Nemours And Company | Purification of tetrahydrofuran |
| JPS6140278A (en) * | 1984-08-01 | 1986-02-26 | Idemitsu Petrochem Co Ltd | Production of tetrahydrofuran |
| GB8717993D0 (en) * | 1987-07-29 | 1987-09-03 | Davy Mckee Ltd | Process |
| DE3726805A1 (en) | 1987-08-12 | 1989-02-23 | Basf Ag | METHOD FOR DISTILLATIVE PURIFICATION OF TETRAHYDROFURANE |
| US4918204A (en) * | 1989-01-30 | 1990-04-17 | Arco Chemical Technology, Inc. | Tetrahydrofuran purification |
| DE3909485A1 (en) * | 1989-03-22 | 1990-09-27 | Basf Ag | METHOD FOR PRODUCING BUTANDIOL-1,4 AND TETRAHYDROFURAN |
| DE4005293A1 (en) * | 1990-02-20 | 1991-08-22 | Basf Ag | PROCESS FOR THE MANUFACTURING OF TETRAHYDROFURAN AND BUTYROLACTONE |
| US5099039A (en) * | 1990-11-06 | 1992-03-24 | Hoechst Celanese Corp. | Production of the from 1,4-butanediol using a polybenzimidazole catalyst |
| US5166370A (en) * | 1991-04-12 | 1992-11-24 | Arco Chemical Technology, L.P. | Preparation of tetrahydrofuran using a supported transition metal |
| AU4110096A (en) * | 1994-11-08 | 1996-05-31 | E.I. Du Pont De Nemours And Company | Process for the removal of color forming material from 1,4 butanediol and its application to the preparation of ptmeg |
| US6159345A (en) * | 1998-11-06 | 2000-12-12 | Mitsubishi Chemical America, Inc. | Method and apparatus for recovering and/or recycling solvents |
| JP2006137749A (en) * | 2004-10-14 | 2006-06-01 | Mitsubishi Chemicals Corp | Method for decomposing ester oligomer and method for producing 4c compound |
| WO2010054976A1 (en) * | 2008-11-17 | 2010-05-20 | Basf Se | Process for preparing tetrahydrofuran |
| KR101398614B1 (en) * | 2009-10-30 | 2014-05-23 | 가부시키가이샤 히타치세이사쿠쇼 | Process and system for purification of tetrahydrofuran |
| JP5817189B2 (en) * | 2011-04-11 | 2015-11-18 | 三菱化学株式会社 | Method for producing tetrahydrofuran |
| JP2012236819A (en) * | 2011-04-27 | 2012-12-06 | Mitsubishi Chemicals Corp | Method for producing tetrahydrofuran |
| JP2012250967A (en) * | 2011-06-07 | 2012-12-20 | Mitsubishi Chemicals Corp | Manufacturing method for tetrahydrofuran |
| JP2012250966A (en) * | 2011-06-07 | 2012-12-20 | Mitsubishi Chemicals Corp | Manufacturing method for tetrahydrofuran |
| JP2013060429A (en) * | 2011-08-23 | 2013-04-04 | Mitsubishi Chemicals Corp | Method of purifying 1,4-butanediol and method of manufacturing tetrahydrofuran |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA546591A (en) * | 1957-09-24 | O. Wolf Herbert | Purification and dehydration of tetrahydrofuran | |
| US2544899A (en) * | 1949-06-01 | 1951-03-13 | Eastman Kodak Co | Method for making cyclic ethers |
| GB1170222A (en) * | 1968-06-10 | 1969-11-12 | Shell Int Research | Process for the preparation of Tetrahydrofuran and/or Homologues thereof |
| JPS4920581B1 (en) * | 1969-08-14 | 1974-05-25 | ||
| US3726905A (en) * | 1971-07-01 | 1973-04-10 | Du Pont | Conversion of butanediol to tetrahydrofuran in the presence of tall oil |
| DE2442886B2 (en) * | 1974-09-07 | 1976-09-30 | Basf Ag, 6700 Ludwigshafen | METHOD FOR MANUFACTURING TETRAHYDROFURAN |
-
1976
- 1976-02-04 JP JP1107876A patent/JPS5293763A/en active Granted
-
1977
- 1977-01-26 GB GB3212/77A patent/GB1502591A/en not_active Expired
- 1977-01-28 US US05/763,506 patent/US4093633A/en not_active Expired - Lifetime
- 1977-02-02 IT IT67215/77A patent/IT1082522B/en active
- 1977-02-02 NL NLAANVRAGE7701056,A patent/NL187911C/en not_active IP Right Cessation
- 1977-02-03 DE DE2704500A patent/DE2704500C2/en not_active Expired
- 1977-02-04 CA CA271,077A patent/CA1099731A/en not_active Expired
- 1977-02-04 FR FR7703191A patent/FR2340314A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| GB1502591A (en) | 1978-03-01 |
| IT1082522B (en) | 1985-05-21 |
| NL187911C (en) | 1992-02-17 |
| JPS5343504B2 (en) | 1978-11-20 |
| JPS5293763A (en) | 1977-08-06 |
| NL7701056A (en) | 1977-08-08 |
| NL187911B (en) | 1991-09-16 |
| DE2704500A1 (en) | 1977-08-11 |
| DE2704500C2 (en) | 1986-01-02 |
| FR2340314A1 (en) | 1977-09-02 |
| US4093633A (en) | 1978-06-06 |
| FR2340314B1 (en) | 1980-12-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1099731A (en) | Process for preparing tetrahydrofuran | |
| EP0601571B1 (en) | Method for purifying 1,4-butanediol, by hydrogenation and distillation | |
| US4652685A (en) | Hydrogenation of lactones to glycols | |
| US6137016A (en) | Process for the purification of butane-1,4-diol | |
| US6426438B1 (en) | Method for producing 1,6-hexanediol and 6-hydroxycaproic acid or their esters | |
| US5214185A (en) | Continuous process for preparing dimethyl carbonate | |
| CA1184202A (en) | Process for continuously preparing ethylene glycol | |
| JPH0635404B2 (en) | Purification method of crude 1,4-butanediol | |
| US5030771A (en) | Method of producing aliphatic and cycloaliphatic diols by catalytic hydrogenation of dicarboxylic acid esters | |
| CA1047049A (en) | Process for producing diacetoxybutane and butanediol | |
| US4656297A (en) | Coproduction of butanediol and tetrahydrofuran and their subsequent separation from the reaction product mixture | |
| US4156685A (en) | Process for producing a hydrofuran and a 1,4-diol | |
| EP0653406A1 (en) | Use of supported rhodium catalysts in the preparation of tertiary butyl alcohol from tertiary butyl hydroperoxide | |
| CA1191871A (en) | Catalytic hydrogenolysis of alditols to produce polyols | |
| JPH0629280B2 (en) | Purification method of crude tetrahydrofuran | |
| JPH0572371B2 (en) | ||
| US4094887A (en) | Process for preparing cyclic ethers | |
| US4962210A (en) | Process for the preparation of high-purity tetrahydrofuran | |
| CA1088084A (en) | Process for producing a cyclic ether from an acetic ester of a 1,4-glycol | |
| EP0012376B1 (en) | Process for producing tetrahydrofuran and 1,4-butanediol | |
| JPH0258262B2 (en) | ||
| JP3995312B2 (en) | Process for simultaneous production of 1,2-butanediol and 1,4-butanediol | |
| US7193091B2 (en) | Method for the simultaneous production of tetrahydrofurans and pyrrolidones | |
| JP3995313B2 (en) | Process for producing 1,2-butanediol and 1,4-butanediol | |
| JP3744097B2 (en) | Method for producing 1,4-butanediol |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |